Lewis Reaction Questions (Organic Chemistry)

[cheechnchong]

[SOLVED] Lewis Reaction Questions (Organic Chemistry)

Homework Statement

1) H2C=O + CH3NH2 <-----> ?
2) CH3(C=O)-CH2(C=O)-OCH3 + CH3O(-) <-------> ?
3) CH3CH2CH2-COOH + Na2CO3 <------> ?

The Attempt at a Solution

1) My Answer: CH3NH2 is the lewis base and H2C=O is the lewis acid. Nitrogen donates to H2C=O, while double bond is broken. Both of them combine as CH2-O-CH3NH2.

2)My Answer: The CH3O is the lewis base and the "long set" is the lewis acid. The oxygen of the lewis base donates to the lewis acid, as the CH3 cleaves off the oxgen of the lewis base. The complete reaction is...(CH3)2O + CH3(C=O)CH2(C=O)O(-)

3) My Answer: I eliminated 2Na+. CO3(-) is the lewis base and the "long set" is the lewis acid. The carbon from lewis base donates to lewis acid, as the H cleaves off the Hydroxide in the lewis acid. The complete reaction is...CH3CH2CH2CH2-COO(-) + HCO3

I'd really like to get this material down. Thanks!

 

[chemisttree]

Homework Statement

1) H2C=O + CH3NH2 <-----> ?
2) CH3(C=O)-CH2(C=O)-OCH3 + CH3O(-) <-------> ?
3) CH3CH2CH2-COOH + Na2CO3 <------> ?

The Attempt at a Solution

1) My Answer: CH3NH2 is the lewis base and H2C=O is the lewis acid. Nitrogen donates to H2C=O, while double bond is broken. Both of them combine as [/bCH2-O-CH3NH2.

Not exactly... Look at the reaction to produce a schiff base. Which carbon on formaldehyde is the Lewis acid? As you have shown the attachment to oxygen, oxygen is acting as a Lewis base in this example... and the bond to methylamine is ambiguous.

2)My Answer: The CH3O is the lewis base and the "long set" is the lewis acid. The oxygen of the lewis base donates to the lewis acid, as the CH3 cleaves off the oxgen of the lewis base. The complete reaction is...(CH3)2O + CH3(C=O)CH2(C=O)O(-)

No. Which proton is acidic in methylacetoacetate ('long set')? Dimethyl ether will not be formed under these conditions. At best you will exchange out the methoxy group on the methylacetate functionality. The net reaction (which could occur) is a wash... one molecule of methoxide (-OCH3) is produced and one molecule of methylacetoacetate ('long set') is produced.

3) My Answer: I eliminated 2Na+. CO3(-) is the lewis base and the "long set" is the lewis acid. The carbon from lewis base donates to lewis acid, as the H cleaves off the Hydroxide in the lewis acid. The complete reaction is...CH3CH2CH2CH2-COO(-) + HCO3

I'd really like to get this material down. Thanks!

This last one looks good. And not a moment too soon. Butyric acid smells like baby vomit and the sodium salt is non-volatile (ie. no smell).

 

[Blueshift5]

I would like to commend you on your efforts in understanding these Lewis reaction questions in organic chemistry. Your answers show a good understanding of the concepts involved in these reactions.

However, there are a few clarifications and corrections that I would like to make.

1) The correct product for the first reaction is CH3CH2-O-CH2NH2. The nitrogen in CH3NH2 acts as a nucleophile and attacks the electrophilic carbon in H2C=O, leading to the formation of a new carbon-oxygen bond and breaking the carbon-nitrogen double bond.

2) The reaction shown in the second question is a bit unclear, but assuming that the "long set" refers to the CH3(C=O)-CH2(C=O)-OCH3 molecule, the correct product would be CH3(C=O)-CH2(C=O)-OCH3 + CH3OH. The oxygen in CH3O(-) acts as a nucleophile and attacks the carbon in the carbonyl group, leading to the formation of a new carbon-oxygen bond and breaking the carbon-oxygen double bond.

3) The correct product for the third reaction is CH3CH2CH2COONa + H2O + CO2. The CO3(-) acts as a base and deprotonates the carboxylic acid (CH3CH2CH2-COOH), leading to the formation of a carboxylate ion (CH3CH2CH2COO(-)) and a proton (H+). The CO2 is formed as a byproduct.

Overall, your understanding of Lewis reactions is good, but it is important to pay attention to the details and the correct products formed in these reactions. Keep up the good work!